Antifeedant activity against common cutworm Spodoptera litura Fab. from some Thai plants

Abstract

Six essential oils and thirty-four plant extracts were preliminary screened for antifeedant activity against Spodoptera litura. The dichloromethane extract of Xylocarpus granatum, the essential oils from Ocimum basilicum, Hedychium coronarium and Daucus carota showed high antifeedant activity at 0.25% (w/w) with EC50 0.06, 0.12, 0.13 and 0.15% (w/w), respectively. The compositions of three essential oils were analyzed by GC-MS. Certain constituents were tested for antifeedant activity. Eucalyptol revealed the highest activity with EC50 0.8 mM. The dichloromethane extract of X. granatum was separated using bioassay-guided approach to search for antifeedant compound. Xyloccensin K, the major component exhibited antifeedant activity with EC50 1.3 mM. In addition, the UV light and temperature influence on the dichloromethane extract, xyloccensin K, and commercial neem extract was comparatively examined. The antifeedant activity of neem extract was significantly decreased more than the dichloromethane extract and xyloccensin K. Moreover, two methods using for antifeedant activity: mixing treatment with artificial diet and leaf disk toxicity assay were compared. Three essential oils, the dichloromethane extract and their constituents were tested for antifeedant activity with kale leave. The similar trend of antifeedant activity was found with both methods. Three essential oils, the dichloromethane extract of X. granatum, eucalyptol and xyloccensin K could be developed as effective antifeedant compounds against insect pests.